Change VendorProduct to use ProductPreparation model
Write new vendor form (no POST handling yet)
Continue work on new vendor entry
Write New Vendor interface, begin Edit Vendor interface
Make Vendor Edit/Add New interface work and look nice
Write Vendor List view, continue CSS work, create generic template
Make page mobile-friendly
Write New Vendor tests
Write Edit Vendor and List Vendors tests, move New Vendor tests
Fix vendors data entry to pass tests
Update requirements.txt
Merge branch 'develop' into feature/16695

Conflicts:
	whats_fresh/whats_fresh_api/tests/views/test_vendors_products.py
	whats_fresh/whats_fresh_api/views/vendor.py